1504
DANIELSWERN, GERALDINE N. BILLENAND JOHN T. YCANLAN
nones and maleic anhydride in the Diels-Alder reaction. It is not likely that the monomer units in copolymerization actually add to the growing chain as charged particles. However, any tendency of two monomers to act as electron donor and electron acceptor, respectively,28 would be reflected in the contributions of corresponding resonance structures and resultant polarities, both in the monomers themselves and in the radicals terminating in them. Probably the explanation of the selectivity in copolymerization of allyl acetate and maleic anhydride is to be sought along these lines. The scarcity of monomers which behave like maleic anhydride would then be due to the fact that most substances with a similar ability to accept electrons (including the quinones) have enough additional resonance possibilities to make them chain inhibitors rather than copolymerizer;. To be highly selective in the manner of maleic anhydride and yet not an inhibitor requires rather narrow limits of resonance stabilization in molecule and radical.
Summary Maleic anhydride is polymerized a t 55' by benzoyl peroxide, about 29 monomer molecules being polymerized for each peroxide molecule decomposed. Allyl acetate and maleic anhydride undergo rapid arid highly selective copolymerization in the presence? of benzoyl peroxide. The copolymerization i q more rapid a t 30" than the polymerization of either of the monomers separately a t 80'. The peroxirlv decuinposition under these conditions is largely induced by chain transfer, being 196 times ( 2 8 ) Compare Gitwxi dnd Loefler, THISJOURNAL, 62, 1324 (1940)
[ CONTRIBUTION
F R O M EASTERN
Vol. 68
as rapid as in allyl acetate alone. For each peroxide molecule decomposed, 187427 molecules of monomer are polymerized, compared with not over 36 for allyl acetate separately under the same conditions, and a similar figure for maleic anhydride. The copolymer is insoluble in the mixture of monomers and shows only limited solubility in all solvents except water. The copolymer prepared with 4.58% by weight of benzoyl peroxide, a great excess of peroxide, has a molecular weight of about 40,000 in acetone; copolymers prepared with lower peroxide concentrations are too insoluble for osmotic pressure measurements. Measurements in water are difficult to interpret because of ionization of the carboxyl groups in the hydrolyzecl polymer. A study of copolymers prepared with p-chlorobenzoyl peroxide has been made and it is concluded that only about one out of four peroxide molecules decomposing leads to the attachment of a fragment to the polymer. A survey of a few other copolymerizations shows none with the degree of tendency toward 1:l copolymerization exhibited by this system, which yields a 1: 1 copolymer even when the ratio of monomers is originally 1:5 and 5 : 1. This selectivity is not correlated with any abnormal vapor pressures, solubilities, or viscosities of the tnonomer mixtures. The results are interpreted in terms of the mechanism of polymerization, as far as the experimental limitations permit. CAMBRIDGE 38, MASSACHUSETTS RECEIVED*~ APRIL 24, 1946 (29) Original manuscript received September 12, 194:
REGIONAL RESEARCH LABORATORY' ]
Hydroxylation and Epoxidation of Some 1-Ole fins with Per-acids BY DANIELSWERN, GERALDINE N. BILLENAND
In previous publications from this Laboratory, the quantitative hydroxylation of inono-unsaturated fatty materials with hydrogen peroxide in formic acid solution' and epoxidation with peracetic acid in acetic acid s o l ~ t i o n respectively, ,~ were reported. The purpose of the present publication is to describe the results obtained when these reactiotis were applied to straight-chain, 1-olefins. I n our earlier paper,2 i t was tentatively concluded .that the hydrogen peroxide-formic acid hydroxylation reaction, in which formic acid (1) One of t h e laboratories of the Bureau of Agricultural and I n dustrial Chemistry, Agricultural Research hdministration. U. S . Department of Agriculture. Article not copyrighted. ( 2 ) S w e r u , nillen, I'indley xiid Scsnlan. THISJ O U R N A L , 67, 1788 ( I 9 16). ( 3 ) Ilinil c y , Swcrii a n d Scanlati, i b i d . , 67, 412 (lU45).
JOHN
'r. S C A N L A N
serves the dual purpose of solvent and oxygen carrier (performic acid is the intermediate compound), is a general method for the hydroxylation of mono-unsaturated compounds with isolated ethylenic linkages. I n seeking further confirmation of this conclusion, we have applied this reaction to 1-octene, 1-decene, 1-dodecene, l-tetradeccne, 1-hexadecene and 1-octadecene, and we have found that good yields of 1,2-glycols are obtained when only 1.025 to 1.05 moles of hydrogen peroxide is employed for each mole of olefin. The crude, saponified reaction products, obtained in yields of 70% or more, usually consisted of almost pure 1,2-glycols without further treatment. The pure glycols, obtained in yields ranging from 40 to 7OyO,were isolated either by fractional distillation or by rccrystallization from
PER-ACID HYDROXYLATION AND EPOXIDATION OF OLEFI FINS
Aug., 1946
1505
TABLE I
GLYCOLS OBTAINEDBY HYDROXYLATION OF THE C, TO CISSTRAIGHT-CHAIN OLEFI FINS AND
---Crude Yield, 1,2-Glycol
%
glycolsIodine M. p.,5 no. OC.
C -
Yield,
%
WITH
HYDROGEN PEROXIDE
FORMIC ACID hl,.p , , C.
Purified glycols Carbon, % Hydrogen, % Calcd. Found Calcd. Found
7
Hydroxyl, % b Calcd. Found
Octanediol 70 1
